Cellulosic spinning solution



Patented Dec. 1, 1936 UNITED STATES CELLULOSI'C SPINNING SOLUTION Hellmut Siebourg, Elizabethton, Tenn., assignor to North American Rayon Corporation, New York, N. Y., a corporation of Delaware No Drawing. Application July 16 1934', Serial N0. 735,433

3 Claims.

The present invention relates to a process of preparing cellulosic spinning solutions from which low lustre yarns maybe obtained.

One object of my invention has to do with the incorporation of such hydrocarbons into cellulosic spinning solutions which, upon extrusion or molding, yield dull-lustre filaments, yarns, ribbons,. films, and the like.

Another object of the present invention is the provision of noveldelustering agents for cellulosic spinning solutions.

A third object of this invention is a method of controlling the lustre ofcellulosic' products by controlling the size of hollow spaces produced in such: products.

Other objects: of my invention will become apparent to those skilled in the art after a study of the following specification:

In the early days of rayon manufacture the demand-was entirely for yarns having the highest possible degree: of lustre. Later, when it was foundthat highly lustrous rayontoo'clearly indicated its originanartificial fibre-a demand. arose for artificial silk which more closely approximatedtonatur-a-l silk. The earliest attempt to meet the demandof dull-lustre viscose yarn, forexample, was-a method of retaining sulphur particlesin the-fibres by discontinuing the normal desulphurizingstep during its manufacture. Although this yarn showed-decreased lustre, due to scattering: of lightby the sulphur particles, it was not permanent andexhibited an unattractive bloom. Phis method has been improved by dispersing,.instead ofsulphur, fine inorganic and organic particles in cellulosicspinning solutions. Liquid-substances, insoluble'in the spinning solutions, such as hydrocarbons, oils, etc., have also been used as delustering agen'tsfor rayon.

After a-thorough investigation of the effects of hydrocarbons upon viscose and cuprammonium spinning solutions, I have found that hydrocarbon fractions ofa certain boiling point range in combinationwith the aforementioned solutionsresult in rayon products superior to those manufactured until the present time. In addition, a smaller quantity of this-particular fraction will deluster rayon'as effectively as larger amounts of a heavier hydrocarbon heretofore used in the art. It is, moreover;.to be noted that substantially all of the hydrocarbons are removed from my cellulosic products during the-after-treatment thereof.

Mynovel process is especially adapted for the manufacture of soft lustreviscose and cuprammon'ium cellulose products; although other cellulosic spinning r solutions, for example, cellulose esters; .ethers; etc may; be used provided that the hydrocarbon fractions later described do not interfere with the same.

A mixture of petroleum ether, gasoline and kerosene was used to produce various petroleum Table I.Efl'ect of hydrocarbon fractions upon the lustre of rayon Boiling point 7 Gloss in centigrades value 5075 2. 6 75100 2. 4 IOU-125 2. 2 125l50 1. 9 l50175 2. 5 175200 2. 9 200225 3. 2 225250 3. 8

The gloss values obtained distinctly show that the degree of delustering does not increase with the boiling point of the hydrocarbon fractions, and that these fractions do not deluster alike.

Hitherto, it has been considered that in order to produce a dull-lustre cellulosic product, the refractive index of the incorporated particles should differ as much as possible from the refractive index of the cellulose, and all former attempts have been madein this direction. That the refractive index is' not the only factor governing the lustre'o'f c'ellulosic products is probably'an erroneous conclusion is evidenced by results obtained with various petroleum fractions, which results are depicted in the followingtable.

Table II .-Efiect of index of refraction upontha gloss value of: rayon Although the refractive indices of the fractions boiling between 125 C. and 150 C. are higher than those of fractions boiling between 50 C and 125 C., their gloss values are lower. Above 150 C. the curve of gloss values will sharply rise. The delustering effect of the fractions up to" 150 C. was found to be caused, not so much by the petroleum present in the finished products, but by the minute air or gas bubbles remaining in the rayon. This is indicated by the fact that cellulosic products thus delustered, when treated with an approximately 5% sodium hydroxide solution at about 36 to 40 C. for about 15 minums regained some of its lustre due to the closing of some of the air spaces previously produced by the volatilizing oil. This, furthermore, was evidenced by the fact that the weight of the petroleum fractions added was lacking in the net weight of the finished product.

The difference in the delustering effect of the fractions boiling below 150 C., cited above, is caused by the escape of the lower boiling fractions from the cellulosic products in the coagulating step in which the cellulosic material is still plastic enough to close the spaces formerly occupied by the oil droplets. According to my present invention, however, such petroleum fractions are used which do not leave the cellulosic products until they have reached that state of solidity which renders fusing of the hollow spaces impossible, said spaces being originally caused by the escape of delustering agent. The escape of these oil droplets occurs during the aftertreatment at elevated temperatures, especially during the drying and steaming steps.

The following table shows the gloss values obtained after treatment with sodium hydroxide solution, as set forth above.

Table III.GZOss values obtained by closing the air spaces of rayon From the above, it may be clearly seen that the essence of my novel delustering process resides in the use of petroleum fractions, having a definite range of boiling points, in combination with cellulosic spinning solutions, especially viscose and cuprammonium cellulose, to produce soft-lustre products. Petroleum fractions with boiling points ranging from to 175 C. are used as delustering agents for the aforementioned cellulosic products. These fractions may be added to cellulosic spinning solutions in combination with inorganic or organic pigments, preferably with titanium dioxide. I have found by experimentation that 0.35% of titanium dioxide, dispersed without any further additions, in rayon produces a yarn having a gloss value of 3.8. When the identical amount of titanium dioxide is used in combination with about 20 cc. of the aforementioned petroleum fractions (B. P.

100-175 C.) per 4500 cc. of viscose, a product results having a gloss value of 1.7. Thus, by using a minute percentage of a lustre modifying agent, such as a pigment, preferably titanium dioxide, and this particular pertoleum fraction together in cellulosic spinning solutions, a very dull-lustre yarn and the like may be produced at low cost. I wish to emphasize, however, that my invention is not limited to the use of titanium dioxide in com bination with the petroleum fractions, set forth above, since other pigments may successfully replace the same. It is also possible to use organic lustre-modifying agents, such as lanolin, petroleum jelly, waxes, etc., which remain in the cellulosic products, in combination with the petroleum fractions. produces a satisfactory, soft-lustre yarn but substantially prevents the formation of incrustations at the spinning nozzle holes during its manufacture and has a beneficial effect upon the hand of the same. I wish to emphasize, furthermore, that the petroleum fractions, boiling between 100 to 175 C., need not be prepared by distillation in the laboratory, as outlined above, since commercially available petroleum fractions having this range of boiling points, the so-called Solvent naphthas, Hi-flash naphthas, etc., may be used with equal success.

Example Twenty cc. of a petroleum fraction, having a boiling point between 100-175 C. 5000 g. of a viscose solution (4500 cc.) and the mixture rapidly stirred for about 15 minutes. The final particles should average from 5 to 10 mu in size, and should preferably not be larger than 7 to 8 mu. .At a maturity of about 10.8, the

viscose solution is spun into a conventional acid salt bath. Instead of adding the aforementioned fraction to viscose, it may be emulsified with a cuprammonium cellulose solution.

It is to be noted that my novel delustering agents are not only inexpensive, but they also tend to improve the tensile strength of the finished products both in dry and wet state, since it is a well known fact that the physical qualities of cellulosic products diminish by the incorporation of foreign matter in proportion to the amounts added thereto. Since smaller amounts of my novel delustering agents are able to deluster rayon better than larger amounts of agents heretofore used in the art, the aforementioned beneficial results are obtained. In addition the luster of the finished products, may be controlled by the degree of fusion of the air-spaces previously produced by the escape of oil droplets. I wish to emphasize also that the amounts of petroleum fractions added to cellulosic spinning solutions may be varied within wide limits to produce more or less delustered cellulosic products. Modifications may be made in details of the method and the product without departing from the spirit and scope of my invention as defined by the appended claims.

I claim:

l. A spinning solution for the manufacture of soft-lustre products comprising a solution of the group consisting of viscose and cuprammonium cellulose and a petroleum fraction'having a boiling point range of about to C.

2. A spinning solution comprising about 20 cubic centimeters of a .peroleum fraction having a boiling point range of about 125 to 150 C. and about 4500 cubic centimeters of a viscose solution.

3. A viscose spinning solution comprising about 20 cubic centimeters of a petroleum fraction having a boiling point range of about 125 to 150 0., about 4500 cubic centimeters of a viscose solution and a small amount of titanium dioxide.

HELLMUT SIEBOURG.

is added to- Such a combination not only I 

